中国城市污泥有机质及养分含量与土地利用

土地利用是城市污泥的重要处理处置方法，其有机质和养分含量是土地利用中很受关注的问题。关于中国的城市污泥虽然已有不少研究报道，但不同研究结果之间结论并不一致，且缺乏系统的总结。通过系统搜集了20世纪80年代以来全国城市污泥相关的文献资料，重点评述中国城市污泥的有机质含量及其土地利用问题。通过29个城市污泥组成的统计分析发现，中国城市污泥(不包括工业污泥)的有机质平均含量达到384g／kg，全氮、全磷和全钾分别为27、14．3和7g／kg；有机质、全氮、全磷比纯猪粪分别高出1／3～2／3，但全钾比纯猪粪低1／3。中国城市污泥的有机质含量呈逐年增加的趋势，但氮、磷含量变化规律不明显。研究证明，城市污泥在粮食作物、蔬菜、经济作物及园林绿地上使用，具有明显的肥效和改良土壤的效果。近年来，城市污泥中重金属含量越来越低，这有利用促进城市污泥的土地利用，但中国在有机污染物和病原体的危害方面研究相对较少，对城市污泥土地利用的潜在风险仍缺乏长期的定位试验研究。

Contents of organic matter and major nutrients and the ecological effect related to land application of sewage sludge in China

Land application is an important way for treatment of municipal sewage sludge both in China and in the world. Therefore, the contents of organic matter and nutrients in sewage sludges and their effect on promotion of plant growth have been highlighted when they are recycled in lands. There have been some systematic summaries for land application of sewage sludges in developed countries while those have not been reviewed in China though there are some specific research related to their contents of organic matter and major nutrients. Related documents about land application of sewage sludges are summarized in the paper, which focuses on the organic matter and nutrients in sewage sludges and their effects on land application. It shows from the statistical analysis of the contents of organic matter and nutrients in China's municipal sewage sludges from 29 wastewater plants that the average contents of organic matter, total N, total P and total K are 385, 27, 14 3 and 7g/kg, respectively, which are 1/3~2/3 higher than their responding contents in pig manure, respectively. It is found that the average contents of organic matter in the sewage sludges have being increased recently in China. Many supported that the sewage sludges can be applied to agriculture, forestry and horticulture because they benefit soil fertility and plant growth. It is also indicated that the contents of heavy metals have being decreased, since the last two decades. which is beneficial for land application of sewage sludges, However, the studies on harmfulness of organic pollutants and pathogens resulting from land application of sewage sludges are still limited and long term effects of their land application are needed to be understood through long term experiments in China.